DS8907数据手册TI中文资料规格书

描述 Description

General Description
The DS8907 is a PLL synthesizer designed specifically for use in AM/FM radios. It contains the reference oscillator, a phase comparator, a charge pump, a 120 MHz ECL/I2L dual modulus programmable divider, and an 18-bit shift register/latch for serial data entry. The device is designed to operate with a serial data controller generating the neces sary division codes for each frequency, and logic state infor mation for radio function inputs/outputs.
The Colpitts reference oscillator for the PLL operates at 4 MHz. A chain of dividers is used to generate a 500 kHz clock signal for the external controller. Additional dividers generate a 25 kHz reference signal for FM and a 10 kHz reference signal for AM. One of these reference signals is selected by the data from the controller for use by the phase comparator.

特性 Features

■ Uses inexpensive 4 MHz reference crystal
■ FIN capability greater than 120 MHz allows direct synthesis at FM frequencies
■ FM resolution of 25 kHz allows usage of 10.7 MHz ceramic filter distribution
■ Serial data entry for simplified control
■ 50 Hz output for ‘‘time-of-day’’ reference driven from separate low power VCCM
■ 5-open collector buffered outputs for controlling various radio functions
■ Separate AM and FM inputs. AM input has 15 mV (typical) hysteresis